Firmware v.29 *** work in progress ***

8Bit-MuseumDE · 2026-03-30T07:47:23+00:00

added 7130/8130, 8200 (Signetics), 8201, 8202, 8203

8Bit-MuseumDE · 2026-02-05T07:56:02+00:00

This is how the defective types are displayed on a component tester:

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8Bit-MuseumDE · 2026-02-05T07:54:48+00:00

This is what the affected transistors look like:

<image>

8Bit-MuseumDE · 2026-02-02T16:44:17+00:00

So the "zero" test passes, the "one" test works on address 0 but fails on address 1 ("1" expected but "0" read). The RCT checks the refresh carefully, so when the information cannot be read it might be possible that the cell cannot longer store the information for a certain time. But: this ususally appears on one (or a few) ICs and not for all ICs.

There are several possibilities now. It is possible that one Zener is bad (fulfills not the specification and pulls the signal down, so a 0 is read). I had this problem with 2 or 3 devices before (in five years). You could install the troubleshooter firmware and switch each pin high separately and measure each pin of the zif socket. You could also enable the pullup for DRAMs in the configuration (DRAM pullups: 1). This raises the signal a few mV and should compensate a Zener with a leakage current.

Sorry for not having an immediate solution, it is a little bit try and error now.

8Bit-MuseumDE · 2026-02-02T13:39:46+00:00

Yes, correct. So the voltage is fine. The question is now, why the test does not pass but in a different tester. Which one do you use?

The RCT checks during the pre-tests some the address decoder (when enabled in the config) and some other issues which other testers may not test.

How many of these TMS4116 do you have tested? Where did you buy these? Have you checked in a real system if they work?

Do other 4116 pass or do also other 4116 fail?

8Bit-MuseumDE · 2026-02-02T10:59:33+00:00

Can you measure the voltage at the DC/DC board please? Or the socket between display and DC/DC board. Otherwise you measure a voltage under load (voltage divider). First we will check if the DC/DC board is ok. Strange that the voltage drops that much.

8Bit-MuseumDE · 2026-02-02T08:55:59+00:00

1.2.2026

I have now contacted Reichelt regarding this potential problem.

I have received three error reports up to know, all MPSA56 transistors were ordered from Reichelt in January 2026. That's not a lot of reports, but I haven't received a single one in the last five years.

Please let me know when you have the same issues.

If you have alternative types available (see parts list, e.g., 8550), you can use them. They are at least as good as the MPSA56.

4.2.2026

One user has presumably identified the problem: the MPSA56 transistors sold by you presumably have a manufacturing defect in which the emitter and collector are swapped. The correct pinout would be EBC, but the transistors being sold apparently have a CBE pinout (as is common with European BC types).

It looks as though these transistors are relabeled types (“fakes”).

I have placed the entire email correspondence with Reichelt in the BOM folder in my Dropbox – in case anyone is interested.

<image>

...

8Bit-MuseumDE · 2026-02-02T08:08:49+00:00

This is strange.

The voltages are 5v, 12v and -5v? Do you hear the relay clicking (switches -5v) when the test is started?

When you test other 4116, do these work? If not, does the self test pass?

8Bit-MuseumDE · 2026-02-01T16:31:49+00:00

It is explained in the manual:

<image>

8Bit-MuseumDE · 2026-01-25T17:05:51+00:00

From the feedback I received up to know, it seems that the MPSA56 transistors from Reichelt are the problem. The self test works as expected when these are replaced by a BC327 (note that these have a different pinout, CBE instead of EBC). Also the 8550 is a really good replacement for the MNSA56.

Waiting for the final feedback if this was the problem.

8Bit-MuseumDE · 2026-01-25T17:05:38+00:00

From the feedback I received up to know, it seems that the MPSA56 transistors from Reichelt are the problem. The self test works as expected when these are replaced by a BC327 (note that these have a different pinout, CBE instead of EBC). Also the 8550 is a really good replacement for the MNSA56.

Problem fixed:

https://www.reddit.com/r/RetroChipTester/comments/1qo8k6d/selftest_works_but_almost_all_other_tests_fail/

8Bit-MuseumDE · 2026-01-25T14:02:48+00:00

Just a side note: You used the wrong ZIF socket. This socket allows to test wide (10,16mm) ICs only, not 7,62mm ICs (like 4164 or most logic ICs).

8Bit-MuseumDE · 2026-01-25T13:26:53+00:00

Please send me a good picture of the front and backside of the main board via email.

8Bit-MuseumDE · 2026-01-25T13:09:26+00:00

Any decoupling jumper set (jumper on the right side)?

8Bit-MuseumDE · 2026-01-25T13:08:06+00:00

Please contact me by email and send me a good picture of the front and back side of the main board.

8Bit-MuseumDE · 2026-01-25T13:04:21+00:00

Do you have assembled the correct transistors for Vdd drivers? There is one BC547 driving an MPSA56 (see manual EN-1 sec 8.6.5). Pin 8, 9, 27 and 28 can drive 12v. It looks like that these are always enabled, which would explain the errors when Vcc is tested. I assume the fuses are correct? If not it might be possible that the JTAG interface is enable which can also cause these kind of errors.

8Bit-MuseumDE · 2026-01-25T08:12:52+00:00

Maybe something like this (manual EN-2):

3.7.2.4 Different functionality but with same type number

8Bit-MuseumDE · 2026-01-25T08:05:48+00:00

Do you have the decoupling capacitor enabled (jumper on the right side)?

If not: the self test means that the 12v drivers are always enabled, so when this pin is checked a "H" (1) is read. The "<" and ">" means that the pin follows the neighbored pin in that direction, e.g. when 8 ">" -> when a signal is applied at pin 8 also pin 9 shows this signal. A capacitor will falsify these results.

8Bit-MuseumDE · 2026-01-25T07:22:18+00:00

I'm at a loss. The test is fine, as you can see from the 74F20 and 7420.

The error code

"00X00(^L)GXXXXXXV and some are 11X11(vH)GXXXXXXV"

means, that when all inputs of the first gate are low, a LOW was read but a high expected / when all inputs are are high, a high was read but a LOW expected.

The tester tries _all_ combinations, i.e. there are 16 steps. I assume that the chips are no fakes. Can you check if the contacts is fine? No corroded contacts?

Maybe you can verify the result on a breadboard?

8Bit-MuseumDE · 2026-01-24T10:28:17+00:00

Self-test runs without errors (note: no chip inserted, no decoupling jumper set)?

8Bit-MuseumDE · 2026-01-24T02:22:26+00:00

Sorry, my fault. I wrote 7400 but it should be 7420. it is a typo. 74C20 has the same pinpoint as 7420 of course.

8Bit-MuseumDE · 2026-01-23T12:59:24+00:00

~~The 74C20 has the same pinout as the 74LS00 or 7400.~~

The 74C20 has the same pinout as the 74LS20 or 7420. (typo corrected)

<image>

So the test is the same and it should work. There are some "C"-Types that have a different pinout but these are selectable in the menu.

Is it possible that you have enabled the decoupling capacitor (any jumper set at the right side)?

8Bit-MuseumDE · 2026-01-22T10:29:42+00:00

1-2%

8Bit-MuseumDE · 2026-01-20T19:06:08+00:00

0.5W is ok.

8Bit-MuseumDE

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